Position control hydraulic snubber

ABSTRACT

A hydraulic snubber for such use as a door closer in which a main piston connected to an actuator arm slides in a main chamber containing a bypass which, once passed, allows hydraulic liquid to be trapped ahead of the main piston and then actuate a control piston which is reciprocated in a control chamber. From the control chamber there are paths through which hydraulic fluid can flow to a reservoir. One path is an unrestricted passage and the other path is a restricted passage. During part of the movement cycle of the control piston, the hydraulic fluid flows freely through the unrestricted passage until a valve element carried by a separate resiliently mounted shutoff piston closes the unrestricted passage. At this point hydraulic fluid is forced through the restricted passage to the reservoir and retards movement of the control piston, which continues to move relative to the shutoff piston because of the resilient connection between them. Movement of the control piston finally stops when it bottoms against the stationary end of the control chamber. Upon the return cycle, hydraulic fluid first flows freely from the reservoir through the check valve passage to the control chamber while the shutoff valve remains closed and later, when the shutoff valve is opened, the hydraulic liquid also flows freely from the reservoir through the corresponding passage and shutoff valve seat into the control chamber.

United States Patent Primary Examiner-Francis K. Zugel AssistantExaminer-Peter A. Aschenbrenner Attorney-Beehler and Arant ABSTRACT: Ahydraulic snubber for such use as a door closer in which a main pistonconnected to an actuator arm slides in a main chamber containing abypass which, once passed, allows hydraulic liquid to be trapped aheadof the main piston and then actuate a control piston which isreciprocated in a control chamber. From the control chamber there arepaths through which hydraulic fluid can flow to a reservoir. One path isan unrestricted passage and the other path is a restricted passage.During part of the movement cycle of the control piston, the hydraulicfluid flows freely through the unrestricted passage until a valveelement carried 'by a separate resiliently mounted shutoff piston closesthe unrestricted passage. At this point hydraulic fluid is forcedthrough the restricted passage to the reservoir and retards movement ofthe control piston, which continues to move relative to the shutoffpiston because of the resilient connection between them. Movement of thecontrol piston finally stops when it bottoms against the stationary endof the control chamber. Upon the return cycle, hydraulic fluid firstflows freely from the reservoir through the check valve passage to thecontrol chamber while the shutoff valve remains closed and later, whenthe shutoff valve is opened, the hydraulic liquid also flows freely fromthe reservoir through the corresponding passage and shutoff valve seatinto the control chamber.

[72] Inventor George B. Solovieff San Clemente, Calif. [21] Appl. No.840,631 [22] Filed July 10, 1969 Patented Apr. 13, 1971 [73] AssigneeNorris Industries, Inc.

Los Angeles, Calif.

[54] POSITION CONTROL HYDRAULIC SNUBBER 9 Claims, 7 Drawing Figs.

[52] U.S.Cl 16/51, 16/52, 16/58, 16/62, 188/87, 188/94 [51] lnt.Cl E05f3/12 Field of Search 16/51, 52, 56, 61, 62, 58;188/94, 87

[56] References Cited UNITED STATES PATENTS 2,701,383 2/1955 Billeter16/59 3,079,629 3/1963 Millard et a1. 16/52 3,110,924 11/1963 Wartian16/52 3,396,424 8/1968 Russell et al.. 16/51X 3,408,683 11/1968 Zahnl6/5lX 4s 4b 42 5e 57 50 6o 54 9 g; 7 72 6 61 i '70 37 5s 7 POSITIONCONTROL HYDRAULIC SNUBBER Pneumatic and hydraulic controls of sundrytypes have commonly been employed to modify the movement of a mechanicaldrive typified by devices used on doors to modify the swing. Doorsfrequently-making use of such devices are those used in public buildingswhere there is frequent opening and closing of the door and some controlis desirable to prevent the door swinging unrestrained to full openposition. Another frequent use of a device of the type made reference tois on doors which are relatively heavy and where the swing of the doorneeds to be snubbed or restricted as it approaches full open position.

Pneumatic devices heretofore employed have experienced difficulty inproper adjustment and control partly because of the fact that the fluidemployed is air which is compressible. Hence, mechanism employing acompressible gas for the operating fluid must always include mechanicalagencies, sometimes complex and delicate in their adjustment, tocompensate for the compressibility of the fluid. Hydraulic devices whichhave been contrived to meet a similar problem have been to a largedegree complex to the extent that they require servicing on a schedulewhich is too frequent. Where such devices are used in accordance withtheir common purpose, namely on public buildings where the door isopened and closed innumerable times every day, devices needing frequentservicing are highly objectionable.

Further still, inasmuch as such doors vary in weight to a considerableextent and in the type of swing desired, controls which cannot bereadily adjusted in the field to meet each particular need have ahandicap which cannot always be tolerated. Where such controls need tobe removed from the door for adjustment and then replaced, adjustment tomeet an individual need becomes a constantly recurring problem.

It is therefore among the objects of the invention to provide a new andimproved hydraulic snubbing device which is simple in its constructionand positive in its operation in that once adjusted there is littleprospect of the adjustment being disturbed through long periods of use.

Another object of the invention is to provide a new and improvedhydraulic snubbing device, the operation of which can be easily andreadily adjusted from the exterior without need for disassembling anyparts of the device, the adjustment being made possible by use ofordinary tools such as a screwdriver.

Still another object of the invention is to provide a new and improvedhydraulic snubbing device which can be compactly contained within arelatively small housing and which is comprised of parts operating inline so that the machining of the housing is a simple and inexpensiveoperation.

Still further among the objects of the invention is to provide a new andimproved hydraulic snubbing device particularly useful as a control forthe swing of a door which permits the door to swing freely throughout aportion of its opening operation and which thereafter initially slowsdown the swing at a predetermined rate before providing a positive stop.

With these and other objects in view, the invention consists in theconstruction, arrangement, and combination of the various parts of thedevice, whereby the objects contemplated are attained, as hereinafterset forth, pointed out in the appended claims, and illustrated in theaccompanying drawings.

In the drawings:

FIG. 1 is a cross-sectional view through a doorway showing a door inclosed or initial position with a hydraulic snubber mounted thereon.

FIG. 2 is a cross-sectional view similar to FIG. 1 but showing the doorin open position.

FIG. 3 is a longitudinal sectional view through the hydraulic snubbertaken on the line 3-3 of FIG. 1, showing parts in initial position.

FIG. 4 is a longitudinal sectional view similar to FIG. 3, but showingthe parts in one advanced position.

FIG. 5 is a cross-sectional view on the line 55 of FIG. 4.

FIG. 6 is a fragmentary longitudinal sectional view showing the positionof certain parts when the shutoff valve is closed.

FIG. 7 is a fragmentary longitudinal sectional view similar to FIG. 6,but showing the relative position of parts at the end of thedoor-openingcycle.

In an embodiment'of the invention chosen for the purpose of illustrationthere is shown a door 10 mounted upon hinges 11 in a doorframe 12. Aposition-control hydraulic snubber indicated generally by the referencecharacter 15 is shown mounted on the door 10 and provided with an arm 16which is designed for attachment to the doorframe 12, the arm 16 beingattached to the hydraulic snubber 15 through a link 17 at a joint 18.The hydraulic snubber 15 is shown in association with a door and frameby way of example, but the mechanism is such as to be capable ofcontrolling a wide variety of actuators making use of the sameprinciples.

More particularly, the snubber I5 is embodied in a housing 20 whichcontains a main chamber 21 and a control chamber 22. In the chosenembodiment the main chamber 21 and control chamber 22 are in axialalignment as is also a main piston 23 slidably mounted in the mainchamber 21 and a control piston 24 slidably mounted in the controlchamber 22.

The main piston 23 has attached thereto, on the right-hand side asviewed in FIG. 3, a main piston rod 25 on which is a rack 26 whichcooperates with a pinion 27, nonrotatably mounted on a shaft 28 which inturn is nonrotatably attached to the link 17. The shaft 28 rotates in abearing sleeve 30. A seal assembly 31 held in position by a snap ring 32prevents hydraulic fluid in the main chamber 21 from escaping past theshaft 28 and bore 19in housing 20.

Adjacent to the main piston 23 and extending for a portion of the lengthof the main chamber 21 is a bypass passage 33 which has an end 34intermediate opposite ends of the main chamber 21. In the position ofFIG. 3, the bypass passage 33 is open, permitting the main piston 23 tomove freely until it reaches the position shown in FIG. 4, at which timethe bypass passage 33 is closed and hydraulic fluid is trapped between aface 35 of the main piston 23 and a face 36 of the control piston 24. Aspring 37 acting between the face 35 of the main piston 23 and a washer38 retained by a snap ring 39 serves normally to hold the main piston 23in the initial position shown in FIG. 3. v

In the housing 20 is a reservoir 40 of hydraulic fluid from which areseveral paths of communication to the control chamber 22. One of thepaths is a restricted passage 40 in which is mounted a flow regulatingvalve element 42 in the form of a needle valve having a valve stem 43which extends upwardly through a cover 44 for the reservoir 40 so as toexpose a screwdriver slot 45 by means of which the valve element 42 canbe adjusted up or. down to increase or decrease the restriction in therestricted passage 41. A vent hole 46 in the cover 44 allows hydraulicfluid to freely flow into and out of the reservoir 40.

A second path for hydraulic fluid between the reservoir 40 and thecontrol chamber 22 consists of a composite passage comprising atransverse bore 47 in communication with an outer annular recess 48 inan end plug 49, a radial bore 50 and an inner annular recess 51. Anaxial bore 52 in a shutoff valve stem 53 communicates with the innerannular recess 51 through a hole 54. A shutoff valve seat 55 serves theaxial bore 52 and provides direct access into the control chamber 22.

A third path is provided by a check valve passage 56 in which is aconventional ball check 57.

The shutoff valve stem 53 is reciprocatably mounted in an axial recess58 in the end plug 49 where it is adapted to be advanced and withdrawnby threads 59 on the shutoff valve stem 53 engaging similar threads inthe plug 49. The shutoff valve stem 53 is retained from removal byemployment of a snap ring 60 having an opening 61 through the middle toprovide access to a screwdriver slot 62 for adjusting the position ofthe shutoff valve stem 53. Seals 63 and 64 surround the shutoff valvestem 53 to prevent escape of hydraulic fluid. Seals 65 and 66 extendaround the end plug 49 for the same purpose.

In cooperation with the shutoff valve seat 55 is a shutoff valve element67 carried by a shutoff piston 68. The shutoff piston 68 isreciprocatably mounted in a recess 69 in the control piston 24 andspring-urged outwardly by a spring 70 against a snap ring 71 ,whichlimits its outward movement. Holes 72 provide access of hydraulic liquidto the inside of the shutoff piston 68 so as to prevent entrapment ofhydraulic liquid. A spring 73 serves normally to hold the control piston24 against the snap ring 39 in initial position.

In operation it can be assumed that the parts are in initial position asshown in FIG. 3 which would be the position of the parts when used as ahydraulic snubber to control the opening of a door as in FIGS. 1 and 2.As the door 10 is moved through an initial portion of its swing, the arm16 and link I7 are swung at the same time which movement results inrotation of the shaft 28 and also the pinion 7, serving to extend therack 26,, thereby to move the main piston 23 from the position shown inFIG. 3 leftward to the position shown in FIG. 4. There is no restrictionto movement of the main piston 23 during this portion of the cyclebecause hydraulic fluid in the main chamber 21 is free to flow aroundthe main piston 23 through the bypass passage 33. Upon the main piston23 reaching the end 34 of the bypass passage 33, flow into the bypasspassage 33 is stopped and hydraulic fluid trapped between face 35 of themain piston 23 and the face 36 of the control piston 24. Continuedmovement from right to left of the main piston 23 then causes force tobe exerted upon the control piston 24 moving it from right to left asviewed in FIGS. 3, 4, 6, and 7. When movement of the control piston 24begins, hydraulic fluid in the control chamber 22 is free to flowthrough the unrestricted passageway to the reservoir 40 and also throughthe restricted passageway 41, the main flow being naturally through theunrestricted passageway, namely past the shutoff valve seat 55 throughthe axial bore 52, the hole 54 to the inner annular recess 51, thenthrough the radial bore 50, the outer annular 48 and the transverse bore47 into the reservoir 40.

Intermediate opposite ends of the control chamber 22 the shutoff valveelement 67 seats upon the shutoff valve seat 55 thereby closing theunrestricted passage. From this point on, hydraulic fluid must flow fromthe control chamber 22 through the restricted passage 41 past the flowregulating valve 42. Since there is restriction to the free flow ofhydraulic fluid, the rate of movement of the control piston 24 is sloweddown. The control piston 24, however, continues to move relative to theshutoff valve piston 68 and at the same time to build up tension in thespring 70 which tends to hold the shutoff valve element 67 on the valveseat 55 until the left end of the control piston 24, as viewed in FIG.7, stops or bottoms against the end plug 49. Further movement of thecontrol piston 24 is stopped by this engagement, and in view ofentrapment of hydraulic fluid between the pistons 24 and 23 movement ofthe main piston 23 is likewise stopped which causes movement of the door10 to be stopped.

Upon release of the door 10, in the embodiment chosen for illustration,the springs 37 and 73 act to return respectively the main piston 23 andcontrol piston 24 toward their initial positions. During the firstportion of the return movement cycle as the space within the controlchamber 22 enlarges hydraulic fluid will be drawn, partially through therestricted passageway 51, but primarily through the check valve passage56 so that there is no restriction to return movement of the controlpiston 24 to initial position. During the latter portion of the returnstroke, after the snap ring 71 is drawn into engagement with the shutoffpiston 68, the valve element 67 is unseated from the valve seat 55 andthe unrestricted passage opened to the flow of hydraulic fluid from thereservoir 40' the rate of movement allowed the control piston 24 afterthe shutoff valve element 67 seats upon the shutoff valve seat 55, Thisin turn varies the rate of movement of the door 10 through the finalportion of its opening swing, in the chosen embodiment. The point atwhich this restricted movement becomes operative can also be changed byshifting the position of the shutoff valve stem 53 endwise toward eitherthe right or left as viewed in FIGS. 3, 4, 6, and 7. Adjustment ispossible by rotating the shutoff valve stem 53 by use of a screwdriverin the screwdriver slot 62 to either inner or outer positions, therebyeither starting the restricted movement cycle earlier or later than asillustrated in FIG. 6. Both adjust ments as described can be made by useof a screwdriver from the exterior of the housing 20 without there beingany need for removal of any portion of the mechanism or removal of thedevice from its position on the door 10.

While the invention has herein been shown and described in what isconceived to be a practical and effective embodiment, it is recognizedthat departures may be made therefrom within the scope of the invention,which is not to be limited to the details disclosed herein but is to beaccorded the full scope of the claims so as to embrace any and allequivalent devices.

lclaim:

l. A position-control hydraulic snubber comprising a housing having amain chamber and a control chamber therein, a main piston slidablymounted in said main chamber, a control piston slidably mounted adjacentone end of said control chamber and in hydraulic communication with saidmain chamber and a closure structure closing the other end of saidcontrol chamber, an actuator operably connected to said main piston formoving said main piston within said main chamber, a bypass passagearound said main piston having a port intermediate opposite ends of saidmain chamber adapted to be closed by movement of said main piston to acorresponding intermediate position, a reservoir in said housing forhydraulic fluid and passage means interconnecting said reservoir withsaid control chamber, a shutoff stem reciprocatably mounted in saidclosure structure, said shutoff stem having an axial bore therethroughin communication with said control chamber, and an outwardly facingshutoff valve seat for said axial bore, said passage means comprising anunrestricted passage between said reservoir and said axial bore and arestricted passage between said reservoir and said control chamber, ashutoff piston reciprocatably mounted in said control piston and havinga normally open outwardly facing shutoff valve element adapted to seaton said shutoff valve seat, and yieldable means acting between saidshut-off piston and said control piston enabling movement of saidcontrol piston against fluid resistance created by said restrictedpassage after closure of said unrestricted passage by the seating ofsaid shutoff valve element on said shutoff valve seat.

2. A position control hydraulic snubber as in claim 1 wherein there isan adjusting means acting between said shutoff stem and said closurestructure adapted to change the location of said shutoff valve seatwhereby to vary the point where said actuator commences to be subject tocontrol by said restricted passage.

3. A position-control hydraulic snubber as in claim 2 wherein there isaccess means in the housing from the exterior to said shutoff stem.

4. A position control hydraulic snubber as in claim 1 wherein there isan adjustable flow regulating valve in said restricted passage.

5. A position control hydraulic snubber as in claim 4 wherein there isaccess means in the housing from the exterior to said flow regulatingvalve.

6. A position control hydraulic snubber as in claim 1 wherein saidchambers and said pistons are in axial alignment.

7.' A position control hydraulic snubber as in claim 1 wherein there isa check valve passage means between said reservoir and said controlchamber including a check valve acting to allow flow from said reservoirto said control chamber.

9. A position control hydraulic snubber as in claim 1 wherein saidcontrol piston has a position bottomed on said closure structure at aforward end of its stroke whereby to stop motion of said main piston andsaid actuator

1. A position-control hydraulic snubber comprising a housing having amain chamber and a control chamber therein, a main piston slidablymounted in said main chamber, a control piston slidably mounted adjacentone end of said control chamber and in hydraulic communication with saidmain chamber and a closure structure closing the other end of saidcontrol chamber, an actuator operably connected to said main piston formoving said main piston within said main chamber, a bypass passagearound said main piston having a port intermediate opposite ends of saidmain chamber adapted to be closed by movement of said main piston to acorresponding intermediate position, a reservoir in said housing forhydraulic fluid and passage means interconnecting said reservoir withsaid control chamber, a shutoff stem reciprocatably mounted in saidclosure structure, said shutoff stem having an axial bore therethroughin communication with said control chamber, and an outwardly facingshutoff valve seat for said axial bore, said passage means comprising anunrestricted passage between said reservoir and said axial bore and arestricted passage between said reservoir and said control chamber, ashutoff piston reciprocatably mounted in said control piston and havinga normally open outwardly facing shutoff valve element adapted to seaton said shutoff valve seat, and yieldable means acting between saidshut-off piston and said control piston enabling movement of saidcontrol piston against fluid resistance created by said restrictedpassage after closure of said unrestricted passage by the seating ofsaid shutoff valve element on said shutoff valve seat.
 2. A positioncontrol hydraulic snubber as in claim 1 wherein there is an adjustingmeans acting between said shutoff stem and said closure structureadapted to change the location of said shutoff valve seat whereby tovary the point where said actuator commences to be subject to control bysaid restricted passage.
 3. A position-control hydraulic snubber as inclaim 2 wherein there is access means in the housing from the exteriorto said shutoff stem.
 4. A position control hydraulic snubber as inclaim 1 wherein there is an adjustable flow regulating valve in saidrestricted passage.
 5. A position control hydraulic snubber as in claim4 wherein there is access means in the housing from the exterior to saidflow regulating valve.
 6. A position control hydraulic snubber as inclaim 1 wherein said chambers and said pistons are in axial alignment.7. A position control hydraulic snubber as in claim 1 wherein there is acheck valve passage means between said reservoir and said controlchamber including a check valve acting to allow flow from said reservoirto said control chamber.
 8. A position control hydraulic snubber as inclaim 1 wherein there is spring means acting between said housing andrespectively said control piston and said main piston for returning saidpistons to initial position.
 9. A position control hydraulic snubber asin claim 1 wherein said control piston has a position bottomed on saidclosure structure at a forward end of its stroke whereby to stop motionof said main piston and said actuator.